Protective covering for ice removal from airfoils



June 1 1951 A. M. LA RUE 6,330

\ PROTECTIVE COVERING FOR ICE REMOVAL FROM AIRFoILs Fiied March 27, 1947 2 Sheds-Sheet 1 ill::II'IITIIIIIT u E II::II:IIIJ

.Jzzl'aa. jibes? ZZZ L 55:25 27- 5 z:'

A. M. LA RUE June 12, 1951 PROTECTIVE COVERING FOR ICE REMOVAL FROM AIRFOILS Fi1ed March2 1947 2 Sheets-Sheet 2 Zu/EHZEL if W... H E a J m T. m

Patented June 12, 1951 UNITED STATES PROTECTIVE COVERING FOR ICE REMOVAL FROM AIRFOILS Albert MeLa Rue, Akron, Ohio, assignor to The B. F. Goodrich Company, New York, N. Y.,- a

corporation 01" New York Application February 27, 1947, Serial No. 731,179

12 Claims. 1

The invention relates to protective coverings suitable for ice-removal. and especially to inflatable coverings for airfoils and the surfaces of other structures exposed to flow of air under icing conditions.

Prior inflatable coveringshave generally utilized cyclical inflation of tubes in alternation for removing the ice from airfoils; but-under some icin condtions have not been fully e'ilec tive in breaking. the bond of the ice. The prior coverings have depended largelyupon the distention at the tube areasfor cracking and loosening the ice deposited thereon resulting sometimes in pieces of ice'of substantial extent remaining adhered to the coverings despite the inflation and distention actions. The construction -'of such inflatable coverings has. also been found to be relatively expensive and time-consuming and'for someapplications' relatively heavy.

An object of the invention is to overcome the foregoing and other" difficulties and disadvantages of prior inflatable coverings.

Otherobjects are to provide animproved protective covering; to provide for distortion of the covering and for assisting the ice-removing action by compelling shifting movement of the outer surface thereof; to provide for restraining outward distention and separating movement of the outer" wall of the covering coincidentally with effecting a shifting and/or rolling action 1 of the same in the direction acrosstthe'direction of separating movement; to provide for effecting the outward distention and the shifting action at a plurality of adjacent regions of the covering; andrto provide for simplicity of construction,. convenience of manufacture" and for light weight and effectiveness of operation.

These and'other-objects-and advantages of the invention will be apparent" from the following description.

In the accompanyin drawings; which form a part of this specification and in which like numerals are employed to designate like parts throughout the same;

Fig. l. is a perspective View from above of an apparatus or protective covering mounted on the leading edge of an aircraft wing and constructed in accordance with and embodying the invention, parts beingibrokenaway and'in section,

Fig. 2 is a planv view of thecovering before its attachment to the wing, parts beingbroken away,

Fig. 3 is a sectionalview taken alongline 3-3 of Fig. 2-, parts being broken away, I

Fig; 4' is adiagrammatieview of a section. of

the covering like Fig. 3 and having broken-lines showing the position of parts under inflation of the covering,

Fig. 5 is a perspective view from an end of the covering showing the latter in the inflated condition, parts being broken away and in sec-- tion,

Fig. 6 is a view like Fig. 2 but showing a modified construction of the covering, parts being broken away, and

Fig. 7 is a sectional view taken along line l-1- of Fig. 6.

In the illustrative form of the invention-shown in Figs. 1 to 5, the construction of an apparatus or inflatable covering ll! of resilient rubber or other rubber-like material includes restraining means 18 arranged in the covering in a manner to compel Shifting movement of the outer surface of the covering in a chordwise direction under an outward distend-ing movement of the outer surface. rolling, shearing and distorting actions throughout the entire distensible area of the covering to remove the overlying ice-deposit. The covering I0 is mounted on the leading edge of an airfoil or aircraft wing l2, being disposed, for example, at the outboard side of an engine nacelle !3: or other component of the aircraft.-

The covering may be attached to the airfoil in any suitable manner, such as by rubber cement II or other suitable-adhesive.

The covering It] has an inner Wall- [4 of suitable rubber-like material desirably reinforced as by non-stretchable sheet material such, for example, as square-Woven textile fabric iii ofcotton, glass fibers, silk, or other suitable natural or synthetic filamentary material. The inner wall l4 being in adhered relation to the surface of the wing, is thus supported uniformly by the latter.

The coverin [9 also has an outer wall N5 of distortable material, preferably resilient rubber like material, in separated relation with respect to the inner wall I4 for facilitating the outward distention or distortion and separating movement of the outer wall under inflation of the covering. The outer wall I6 may be reinforced with a highly stretchable fabric sheet material ll such, for example, as elastic fabric or stockinet fabric of suitable filamentary material. The stretchable reinforcement assures continuity of transmittal of the separating" and theshift ing movements uniformly throughout-the-rubb'er material of the outer wall.

To the ends of restraining the separating-move The construction thus providesment of the outer wall and compelling lateral or chordwise shifting movement thereof, the inven tion provides the means is comprising a plurality of interposed restraining elements l8, l8 of flexible material connecting the inner and outer walls in an offset manner unidirectionally of the covering, as shown in the drawings. Preferably, the elements l8, iii are in the form of partition elements of flexible strip material such, for example, as woven textile fabric, which fabric may be stretchable or non-stretchable, as desired, and may be made impervious, if desired, as by a coating or impregnation of suitable rubber-like material for providing a plurality of inflatable passages in the covering adapted to be inflated simultaneously or independently, as desired.

The partition elements l8, is are disposed be tween the inner and outer walls l4, l6, and are spaced apart in chorolwise series and extend spanwise in side-by-side, adjacent relation one to an other along the covering throughout the extent of the distensiblc area thereof and substantially coextensive with the length thereof. However, some of the elements at the sides of the covering may be of lesser length to conform to the shape of the covering, as shown especiall in Fig. 2.

For joining the partition elements l8, [8 to the inner and outer walls, each element may be ccmented to the walls or otherwise secured thereto, and may be adhesively attached along side marginal portions i9, 20 of the element as by a suitable rubber cement, as shown especially in Fig. 5. The partition elements are joined to the outer wall along spanwise lines parallel one to another and at positions ofiset chordwise with relation to their positions of joinder with the inner wall in a manner to eflect swinging movement of the partition elements in a chordwise direction under the distention of the outer wall and the separating movement thereof relative to the inner wall to compel shifting movement of the outer wall.

In the embodiment shown in Fig. 2, the shifting movement is all in one fore and aft or chordwise direction or the covering, although other arrangements of shifting movement may be provided, if desired. For example, the partition elements may be onset or shaped in a portion of the covering in a, different and opposite manner from that in another portion of the covering so as to compel the shifting movement of the portions in diirerent directions, such as toward each other or away from each other.

Under inflation of the covering and the separating movement of the outer wall, the partition elements i8, it move with the outer wall and swing about their spanwise lines of joinder to the inner wall from the position adjacent the inner wall, as shown especially in Fig. 3 and in full lines in Fig. 4, to substantially the position shown in broken lines in Fig. 4 and the position shown in in Fig. 5. This swinging action of the partition elements l8, l8 compels shifting movement of the outer wall relative to the inner wall in the opposite chordwise direction to that of the direction of offset attachment, that is, in the direction across the direction of separating movement. The shifting movement occurs concurrently with the distention and rolling action of the outer wall under the inflation of the covering. In this manner, the overlying ice deposit is subjected to lateral or chordwise shearing action b the shifting movement of the outer wall for breaking effec'tively the adhesive bond at the interface between the ice and the outer wall, and in addition the ice deposit is subjected to outward distortion for breaking the ice into pieces and further reducing the adhesive bond of the latter.

For inflating the covering, a flexible conduit or hose 2| is attached to the inner wall I4 in communication with the space between the inner and outer walls, which conduit 2! may be connected to a suitable source of air under pressure inthe structure of the aircraft. The partition elements l8, !8 may be provided with spaced apertures 22, 22 in series along their length in register one to another chordwise of the covering for the purpose of simultaneous inflation of all the passages, as shown especially in Fig. 5. The construction provides for intercommunication of the inflatable passages one to another through the walls thereof, that is the partition elements, facilitating the separating movement and shifting movement of the outer Wall IE simultaneously throughout the extent of the covering under inflation for effecting complete and prompt .removal of the ice-deposit. The covering may be rectangular or tapered or otherwise suitabl shaped in form to conform to the shape of the wing and to provide the de sired extent of chord-coverage of the win The Y partition elements adjacent the spanwise attaching margins 23, 24 may be of shorter length than the partition elements inwardly of the flrst said partition elements, when the covering is tapered in form. The fabric and rubber parts of the covering Ill are united integrally and, desirably by vulcanization under heat and pressure. The construction described hereinabove provides for light weight and strength for the purpose in combina tion with thinness and flexibility and smoothness of the covering facilitating convenience of attach ment and smooth conformance of the covering to the surface of the leading edge, which conformance is advantageous for maintaining the aerodynamic characteristics of the wing.

In the operation of the covering I0 thus mounted on the leading edge of the wing, the admittance of air under pressure through the conduit 2! to the space between the inner and outer walls of the covering inflates the latter simultaneously throughout the distensible area occupied by the partition elements l8, l8. Since the inflatable passages provided by the plurality of the partition elements I8, l8 are in communication with one another, all of the passages are inflated simultaneously, resulting in the outward distention or bulging and separating movement of the entire outer wall at the distensible area. The separating movement of the outer wall causes the entire chordwise series of interposed partition elements to swing about their spanwise lines of joinder with the inner wall and thus limit the extent of the separating movement coincidentally with compelling shifting of the outer wall relative to the inner wall in the opposite chordwise direction with respect to the chordwise direction of offset attachment of the partition elements to the inner and outer walls.

The inflation thus distends the outer wall I6 into a chordwise series of spanwise extending outward bulges which rapidly change contour during the inflation to assume a substantially ridgelike form having sharp radius of curvature, each bulge being formed intermediate the respective lines of joinder of the partition elements i8, 8 to the outer wall. The bulging or distending action of the outer wall taking place coincidentally with the swinging movement of the partition elements effects a rolling action of the outer wall at each bulge during the formationlof the latter,

whileetheswinging: action of the partition elements .com'pelsilateral or chordwise vshiitingmovement of the. outer: wall. effecting a. shearing ac;- tion...on.the; adhesive bond. at the interface betweentheice. and the covering at. eachv minute area orthe outer wall overlying the partition elements. .The aforesaid. outward distention and separating movement of the outer wall, in combination with theshifting movement. thereof thus effect. breakageof. the. adhesive bond and in addition break the overlying ice deposit into. pieces for prompt and thorough removal. of the ice by thejscavenging. action of the fiow of air across the wing.

The modified construction 25 of the covering, shown in Figs. Sand 7,, is substantially like that described hereinabove for the covering l0 except that the interposed partition elements 2.6, 21 havea different offset. attaching arrangement and, unlikethe partition elements I8, l8, dov not extend continuously from end to endof the'covering. but are .ofrelatively short spanwise extent. The outer wall 15 is arranged in a plurality of panels 28, .29 spaced apart spanwise and extending chordwise of the covering in parallel relation one to another, and a plurality of the interposed partitionelements 25', 21 are disposed at each of the panels.-

v'Ihepartition elements 26, v2'! are positioned spaced-apart in chordwise series and extend s'panwise of the covering coextensive with the spa-nwise extent of eachv panel, as shown especially in Fig. 6, providing inflatable passages in communication with one another at the respective ends of each of the chordwise series of partition elements; Preferably, although not necessarily limited thereto, the partition elements 26, 21 are not apertured but present anunbroken Wall throughout:- their spanwise extent.

'I he interposed partition elements 26, 2! are joined to the inner and outer walls I4, H5, respectively, in an offset attachment arrangement to; effect the desired swinging action of the partition elements 26, 21. The partitionv elements 26:, .21 are constructed and arranged at adjacent panels 28, 2!! in a manner to-compel the shifting oi theouter wall H5 at such adjacent panels in opposed chordwisedirections, as indicated by the arrows at 31 and3i. The arrangement. is such that the chordwise offset attachment of. the partition elements 26 is opposite that of the chordwise; offset: attachment of the partition elements 21,.as shownespecially in Fig. 7.

Under inflation of the covering 25, the outer wall. l5. at the respective panels 28, 29; is bulged outwardly, as describedhereinabove, forthecovering: I0, while" the: shifting movement at the. adjacent panels 28', 29.0ccursin opposedw chordwise directions. This resultsadvantageously in. combining a twisting action at the outer wall withthe desired outward distention and separating movement thereof and the shifting movement thereof in a chordwise direction, all of which effectively breaks the adhesive bondbetween the ice -and the covering and" breaks the ice into pieces for removal by the scavenging effect of' the flow of air;

Variations may be made without departingv from the scope of the invention. as it is defined in the following claims. 7

1. Apparatus for preventing the accumulation of iceupon a surface, said apparatus comprising a covering having an inner wall, an'outer wall of distortable material in separated relation with 6'. respect to said inner: walL. means for: efiecting separating movement of said'out'er wall. relative:

to said inner wall, and interposed:restrainingielain'ents connecting said walls and joined to said compel shifting of'said outer wall relative to said inner wall unidirectionally of the covering 'inthe direction opposite with respect to the direction of offset and across the direction of said separating movement. 7 I

2. Apparatus for preventing the accumulation of ice upon a surface, said apparatus comprising a covering having an inner wall, an outer wall of elastic material in separated relation with respect to said inner wall, means for 'di'stendin'g said outer wall andefiecting separating movement thereof relative tosaid inner'wall, and in-- terposed restraining elements of flexible mat'e V rial connecting said walls and joined to said outer wall at positions offset unidirectionally of '-the covering with relation to their positions of joinder with said inner wall in a manner to" effect inner wall unidirectionally of the covering in the direction opposite with respect to the direction of' offset and across the direction of said separating movement. I I

3. Apparatus for preventing the accumulation of ice upon a surface, said apparatus comprising an inflatable covering having'an inner wall, an"

said outer wall at positions offset in thedirection toward a margin of the covering with relation to their positions of joinder with said inner wall in a manner to effect swinging movement of said elements under the distention and separat ing movement of said outer wall to compel shifting. of said outer wall relative to said inner wall.

in the direction opposite with respect to said direction toward said margin of the covering and across the direction of said separating movement. 4. Apparatus for preventing the accumulation of ice upon a surface, said apparatus comprising a covering having an inner wall, an outer wallj of distortable materialin separated relation with respect to'said inner wall, means for distorting said outer Wall andefiecting. separating movement thereof away from said inner wall, and interposed partition elements of strip material.

extending side-by-side in said coveringin a di-- rection thereof in spaced-apart relation one toanother and connecting said walls and joined to said outer wall at positions offsetin a direction across the first said. direction with relation to their positions of joinder with" said innerwallin a manner to effect swinging movement of said elements under said separating movement of said outer wall to compel shifting of said outer wall. relative. to" saidinner wall in the direction opposite with respect to the. direction; of ofiset" and across the directioniof said separating move' ment.

5; Apparatus for preventing the accumulation of ice upon the leading edge of an airfoil, said apparatus comprising an inflatable covering of resilient rubber-like material for said leading edge having an inner wall, an outer wall of said material in separated relation with respect to said inner wall, means for inflating said covering to distend saidouter wall and effect separating movement thereof away from said inner wall, and a plurality of interposed partition elements of flexible strip material extending in side-byside relation one to another along said covering and disposed spaced-apart in series across the covering providing a plurality of inflatable passages, said elements connecting said walls and being joined to said outer wall at positions offset in a direction across the covering with relation to their positions of joinder with said inner wall in a manner to effect swinging movement of said elements under inflation of said passages and said separating movement of said outer wall to compel shifting of said outer wall relative to said inner wall in the opposite direction with respect to'the first said direction across the covering.

6. Apparatus as defined in claim 5 in which partition elements extend spanwise along the covering in series chordwise thereof and the joining positions of said elements with said walls of the covering are offset in a chordwise direction.

7. Apparatus as defined in claim 5 in which said partition elements are joined to said walls along lines parallel one to another and offset in a direction normal to said lines.

8. Apparatus as defined in claim 5 in which said partition elements extend spanwise along the covering in series chordwise thereof and are joined'to said walls along spanwise lines parallel one to another and offset in a chordwise direction providing a plurality of inflatable passages in chordwise series extending spanwise of said ooveringfsaid passages being in communication one to another for simultaneous inflation of said covering.

9. Apparatus for preventing the accumulation of ice upon the leading edge of an airfoil, said apparatus comprising a covering of resilient rubber-like material for said leading edge having inner and outer walls in separated relation one to another, the outer wall having a plurality 'of panels of said material spaced apart spanwise and extending chordwise of the covering in: parallel relation one to another, means for inflating sad covering to distend said outer wall and effect separating movement thereof away from the inner wall, and a plurality of interposed" partition elements at each of said panels disposed spaced-apart in chordwise series and extending spanwise of the covering providing inflatable passages in communication with one another, said elements connecting said walls at each of said panels and joined to said outer Wall along spanwise lines parallel one to another and at positions offset chordwise with relation to their positions of joinder with said inner wall in a manner to eifect swinging movement of said elements under the separating movement of said outer Wall to compel shifting of said outer wall at said panels thereof relative to said inner wall in a chordwise direction of the covering, said elements being constructed and arranged at adjacent panels in a manner to compel the shifting of said outer wall at said adjacent panels in opposed chordwise directions.

10. Apparatus for preventing the a'ccumulation ofiice upon a surface, said apparatus comprising a covering having an inner wall, an' outer wall of distensible material in separated relation with respect to said inner wall, means for distending said outer Wall and effecting separatingv movement thereof relative to said inner wall,

and a plurality of interposed restraining elements connecting said walls and joined to said outer wall at positions offset unidirectionally of the covering with relation to their positions of joinder with said inner wall in a manner to effect swinging movement of said elements under the separating movement of said outer wall and to facilitate localized distension of said outer wall at portions thereof intermediate the positions of joinder of said elements with said outer wall.

11. Apparatus for preventing the accumula-' tion of ice upon a surface, said apparatus Comprising a covering having an inner wall, an outer wall of elastic material in separated relation with respect to said inner wall, means for distending said outer Wall and effecting separating movement thereof relative to said inner wall, and a plurality of interposed restraining elements of elastically stretchable material connecting said walls and joined to said outer Wall at positions offset unidirectionally of the covering toward a margin of the covering with relation'to their 12. Apparatus for preventing the accumulation of ice upon a surface, said apparatus comprising a covering having having an inner wall,

an outer Wall of distensible material in separated relation with respect to said inner wall, and

means for distending said outer wall and effecting separating movement thereof away from said inner wall, and a plurality of interposed partition elements of stretchable strip material including elastic material extending side-by-side in said covering in spaced-apart relation one to another and connecting said walls and. joined to said outer wall at positions offset unidirectionally of the covering toward a margin of the covering with relation to their positions of joinder with said inner wall in a manner to'eifect swinging movement of said elements under the separating movement of said outer wall and to facilitate by virtue of the stretchability of said elements localized distension of said outer wall at portions thereof intermediate the positions of joinder of said elements with said outer wall.

ALBERT M. LA RUE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,306,759 Sears Dec. 29, 1942 2,418,262 Hunter Apr. 1, 1947 2,440,240 Antonson Apr, 27, 1948 2,440,533 Antonson Apr. 27, 1948 2,446,328 Heston Aug. 3, 1948 

